特征参数

In this dissertation , the methods of prediction and parameters\' estimation based on stationary multivariate autoregressive models AR(p are studied systematically. Some properties of these methods are formulized.In the first part, it introduce some basal conceptions about multidimensional stationary time series, contained the estimation and property of mean vector and auto-covariance function. Then the stable condition of multidimensional AR models are discussed.

本文主要研究了多维平稳序列自回归模型AR的参数估计及其相关的统计性质，具体内容如下：第一部分，介绍了多维平稳时间序列及其均值向量和协方差阵函数的概念，并引入了多维AR模型及其数字特征，在此基础上给出了模型的平稳性条件。

A review of river management history in various countries is used in this thesis to discuss the future development trends of river management and the relationship between river health and river management.Based on the characterization and assessment of river health, Five components of stream condition are presented in this thesis to characterize river health: water quality, aquatic life, physical form, hydrology and streamside zone. It is obtained by comparing the methods and criteria that have been developed by others and reviewing the river assessment practices in various countries. Accounting for the features of urbanization region in plain river network, an indicator system for river health assessment which provides scores for 5 subindices and 17 indicators is established. With almost 200 stream reaches in Shanghai as objective of study and Liwa stream and Zhangjiabang Creek as case study, the application of river health assessment in the planning, baseline survey and post-project appraisal of river management is explored by collecting historical literature and field monitoring. Consequently, some suggestions to improve river management effectiveness are presented from the angle of river health.

本文回顾河流管理漫长历程并指出当前国际发展趋势，进而辨析河流健康状况与河流管理的关系；以河流健康状况的表征和评价为核心，通过对国外RIVPACS、AUSRIVAS、IBI、RCE、ISC等河流健康状况评价方法的分析和比较，以及对美国、英国、澳大利亚、南非等国家河流健康状况评价实践的总结，尝试从理化参数、生物指标、形态结构、水文特征、河岸带状况5个方面全面表征河流健康状况；结合中国东部平原河网地区自身特点，通过评价原则、评价指标、评价标准、评价权重确定等步骤，初步构建了包含河流水文、河流形态、河岸带状况、河流水质以及河流生物5个一级指标(共17个指标)的河流健康状况评价指标体系；在此基础上，采用资料收集与现场实测相结合的方法，以上海近200条中心河道为研究对象，以丽娃河和张家浜为典型案例，分别就河流健康状况在河流管理规划、现状评估以及后评估中的应用进行实证研究，并尝试探讨如何从这三个阶段利用河流健康状况评估改进河流管理的对策。

By representing the uncertain parameters as interval numbers, the interval dynamic characteristic equations and the dynamic governed equations of the structure are built by means of the interval finite element method.

基于区间模型的结构动力分析将结构中的不确定性参数用区间数来表示，建立了系统的区间动力特征方程和动力控制方程。

In recovering a low dimensional parametrization of data lying on a low dimensional submanifold in high dimensional space, we need to understand and grasp the structure of image of the Laplacian Eigenmap.

在揭示建立在高维数空间中的一个低维子流形中的一个低维数的确定参数时，我们需要去了解并领会拉普拉斯特征映射的像的构造。

This method not only can reduce the dimension of feature vector effectively,but also can provide a new kind of parameter for recognition of protein superfamily.

此方法不仅有效地降低了特征向量的维数，而且为蛋白质超家族识别提供了新的参数。

In this paper,the principle and primary results of measure ultrasonic sound velocity and attenuation coefficient by ultrasonic syntonic method are introduced.

1 前言各种介质的声学特性主要由声速、声衰减、声阻抗等参数来描述，这些量统称为介质的声学特征量。

The algorithm of the static voltage stability region s tangent plane through the characteristic vector method or the implicit function derivative method is presented in the total parameter space,which can provide quantitatively the influence degree of all kinds of parameters on the voltage stability region.

提出了基于全参数空间的静态电压稳定域的2种切平面计算方法：特征向量法和隐函数求导法。

Three-dimensional morphological structures of leaf,stem,tasse...

其中，玉米叶片、茎节、雄穗、雌穗和根系的三维形态是由基于器官形态结构主要特征而构建的参数化的几何模型来描述的。

the article examines the characteristics of foreign exchange returns distribution,coupling with kinds of foreign exchange datas, figures out parameters of model by using variance gamma model.the empirically results ofkolmogorov-smirnov test and goodness of fit chi-square test shows that v.g.

本文运用方差gamma模型对外汇收益分布特征进行对比拟合分析，并结合几种被选汇率数据对模型参数进行估计。ks检验和卡方拟合优度检验的实证结果表明v.g。

In this paper, nanopowders of rare earth oxides and tungsten were prepared and 0-3 type nano-composit rare earth tungsten thermionic emission materials were fabricated with novel technics. The raw material selection, preparation technic parameter, structure, physical and chemical characteristic, the rare earth distribution and the emission behavior were studied. The influence between the active layer and the thermionic emission performance, rare earth elements diffusion and distribution along depth were investigated in detail. The surplus RE formation and the electron transfer were discussed in theoretically. The thermionic emission current density of the single surplus RE on the active layer was educed. We adopted "liquid-liquid mixing, freeze-drying and two stage-reduction" working step firstly to produce the RE-W nanopowders including La-W powder, Ce-W powder and Y-W powder.

本文采用细化显微组织的新工艺，制备了纳米稀土钨粉末和0-3型纳米复合稀土钨热电子发射材料，探讨研究其原料选择、制备工艺及参数、结构特征、物理和化学特性、稀土分布均匀性、以及热电子发射特性；系统研究了稀土元素的高温扩散情况、高温状态下活性层中稀土的纵向深度分布、以及表面活性物质和活性层厚度对热发射性能的作用；从理论上分析阐释了超额稀土的形成及其电子的传递过程；并从理论上推导了活性层中单个超额稀土的热电子发射电流密度。

According to the clear water experiment, aeration performance of the new equipment is good with high total oxygen transfer coefficient and oxygen utilization ratio.

曝气设备的动力效率在叶轮转速为120rpm～150rpm时取得最大值，此时氧利用率和充氧能力也具有较高值。

The environmental stability of that world - including its crushing pressures and icy darkness - means that some of its most famous inhabitants have survived for eons as evolutionary throwbacks, their bodies undergoing little change.

稳定的海底环境─包括能把人压扁的压力和冰冷的黑暗─意谓海底某些最知名的栖居生物已以演化返祖的样态活了万世，形体几无变化。